Oh boy, michaelochurch. His experience was extremely atypical. He had a legitimately awful time at Google. I don't know what happened between him and his manager and team so I can't say who or what was to blame. But I think he was put on a performance improvement plan (whether fairly or unfairly). And I think it would make sense to most people that an employee on a performance improvement plan would be strongly discouraged from expanding into a 20% project until their performance improves.
FYI, when it comes to reading any Michael Church claim, especially one about working at Google, I'd put more weight on the "outspoken" than the "ex-Googler." He admitted himself on HN that he engaged in what he called "white hat trolling" while at Google, a pattern he seems to have repeated throughout his life.
He's very articulate, but he has an EXTREMELY strong belief in the quality and accuracy of his own ideas. For illustration, he wrote a few months ago, "societies live or die based on what proportion of the few thousand people like me per generation get their ideas into implementation." When presented with such self-confidence beyond all reasonable proportion and corroborating evidence, I think an appropriate response is skepticism.